Ohmage Mismatch/Tone

What am I sacrificing by using a Mark V head at 8 ohms into a 16 ohm 4x12? I know it is a safe mismatch but by not having an exact match cabinet in 8 ohms I cannot know

When I accidentally ran an 8 ohm cab off the 4 ohm output of my Mark 3 (simulclass), I seemed to lose some volume.

Not sure if this explains it. In dc circuits the bigger the load (higher resistance) the bigger the voltage drop = more power consumed. The speaker being an ac circuit I think it does the same with resistve loads but in a different way dependent on frequencies and some rms formula. That may explain a drop in volume. However as with most things I foolishly attempt to apply logic to, the opposite is generally the case. So it could be that the greater the power drop at the coil may make it easier to push and pull the cone!

Pretty sure that doesn't explain it!

Aagh! Somebody shoot me!

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The lower the impedance of the cab, the harder the tubes and output transformer have to work to produce low frequencies. Low frequencies consume the vast majority of power, so mids and highs are largely unaffected.

This means that if you put a lower impedance cab on a normal output (4 Ohm cab on 8 Ohm out) you will likely hear less bass, since the 8Ohm transformer tap has trouble driving the 4 Ohm load.

If you put a 16 Ohm cab on an 8 Ohm tap, it can drive lows much more easily, so it will sound more bass-heavy.

If your cab also has a 4 Ohm mode, you can plug that into the 4 Ohm speaker out and get a proper impedance match.

elvis said:

If your cab also has a 4 Ohm mode, you can plug that into the 4 Ohm speaker out and get a proper impedance match.

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Yeah, in the long run this might be your best option - even if it doesn't have 4 ohm switch/jack, a 16 ohm 4x12 can be easily rewired to 4 ohms.

You're not sacrificing anything. I ran my Mark IV and now my Mark V:25 into a Bogner 4x12 at 16ohms for a long time. Sounds great.

CudBucket said:

You're not sacrificing anything. I ran my Mark IV and now my Mark V:25 into a Bogner 4x12 at 16ohms for a long time. Sounds great.

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If it sounds good... it is good.

I tried plugging the 8ohm C90 speaker of my Rocket 44 into one of the 4 ohm jacks just to try it out. Had a warmer and looser bottom end response. Tops where a little bit fizzier.